The invention relates to a heat exchanger, in particular a brazed heat exchanger suitable for use in motor vehicles, and to a pipe junction element for such heat exchangers.
Heat exchangers, in particular radiators or heaters for motor vehicles, have flowing through them on the primary side a fluid, in particular the motor vehicle engine coolant. Connection to the coolant circuit takes place via junction or connection pieces on the heat exchanger which are connected to pipe junction lines for the coolant. Various pipe junction connections are known, depending on the type of construction of the heat exchanger or of its header tank, on which the junction pieces are located. The commonly assigned DE-A 35 17 488 discloses a heat exchanger with a plastic water tank having junction pieces injection molded onto the tank. Coolant junction pipes are inserted into these junction pieces and are secured via a securing clip, which may be referred to as an insertion fork. Similar pipe junction connections are known from commonly assigned DE-C 197 37 704. Where brazed heat exchangers are concerned, both the water tank and the junction pieces which are brazed into the water tank also consist of metal, preferably of aluminum. The insertion fork connection known for plastic junction pieces is transferred in modified form to metallic junction pieces, as proposed in DE-A 44 03 402, DE-C 196 21 282 or DE-A 197 40 115 or DE-A 197 52 139.
Another form of a pipe junction is known from commonly assigned DE-A 196 48 162, specifically for a brazed heat exchanger with junction pieces brazed into the water tank. The coolant junction pipes are inserted into the junction pieces and sealed off by means of O-rings, axial fixing of the junction pipe in the junction piece located on the heat exchanger side taking place by means of what may be referred to as a holding clip ring which engages over an annular bead on the junction pipe and an annular flange on the junction piece. This type of insertion connection permits rapid mounting, that is to say a rapid junction of the coolant tubes to the heat exchanger in the vehicle. In order further to simplify mounting, it is also known to connect the coolant junction pipes to the heat exchanger via a flange, in which the inflow pipe and return pipe are combined. In this case, the heat exchanger has provided on it a first flange which is connected to a second flange in the vehicle in order to produce the coolant junction. For brazed heat exchangers, it is known to produce the flange as an aluminum part which is brazed to the heat exchanger. This brazing or soldering is relatively costly.